It is often necessary to install branch connectors on pipes, such as the pipes used for distributing gas and water. In built-up areas, it is desirable to dig excavations of small size in order to limit the inconvenience caused to pedestrian or vehicle traffic. There is therefore no question of digging a trench large enough to allow a person to go down to the bottom of the trench, so it must be possible for the operations of installing the connector to be performed from the top of the excavation.
When the pipe and the branch connector are made of a hot-melt material such as polyethylene, the connector is generally secured to the pipe by welding. The body of the branch connector is saddle-shaped and is fitted with an electrical resistance connected between two power feed terminals for connection to an electricity power supply for performing the welding operation by melting the saddle of the connector and welding it onto the portion of the length of pipe which is in contact with the saddle. In order to ensure that the welding operation is performed properly, it is necessary for the branch connector to be held pressed against the pipe. For that purpose, a bottom saddle is provided which is placed beneath the pipe and which is connected to the top saddle belonging to the body of the branch connector. By connecting together the bottom saddle and the body of the branch connector fitted with the welding means, it is possible to guarantee clamping against the pipe under conditions that are well defined and reproducible, thus making it possible to obtain an approved assembly between the branch connector and bottom saddle.
Proposals have already been made, in particular in documents FR-A-2 714 710 and EP-A-0 205 696 for equipments making it possible to install a saddle-shaped branch connector on a pipe from the top of an excavation dug around the zone in which the connector is to be installed, thereby making it possible to dig an excavation of small dimensions given that it is no longer necessary for a person to go down to the bottom of the excavation.
Nevertheless, those prior art equipments remain quite complex and therefore quite expensive, and they are also tied up throughout the welding operation, given that they contribute to exerting a clamping force on the branch connector. The use of such equipments also makes it necessary to perform various tests in order to guarantee that the weld is of good quality, which is essential when the pipe is for distributing gas, since there must be no risk of a leak.